Simulations of Sisyphus cooling including multiple excited states

We extend the theory for laser cooling in a near-resonant optical lattice to include multiple excited hyperfine states. Simulations are performed treating the external degrees of freedom of the atom, i.e., position and momentum, classically, while the internal atomic states are treated quantum mechanically, allowing for arbitrary superpositions. Whereas theoretical treatments including only a single excited hyperfine state predict that the temperature should be a function of lattice depth only, except close to resonance, experiments have shown that the minimum temperature achieved depends also on the detuning from resonance of the lattice light. Our results resolve this discrepancy.Comment: 7 pages, 6 figure

The Renewed Need for Guidance Addressing Partnership 754 Election Revocations

The section 754 election of the Internal Revenue Code allows partnerships to make basis adjustments to avoid potentials for double taxation that can arise following transfers of partnership interests and distributions of partnership property. Once made, a 754 election applies to all future tax years and is revocable only with the consent of the Internal Revenue Service (Service). One subsection of the Treasury Regulations addresses when the Service might approve or deny a partnership’s request to revoke a 754 election. Despite the process contemplated in this regulation, until recently, partnerships could default out of a 754 election without Service approval through a technical termination. The lack of recorded application of the regulation implies that partnerships have largely not needed to rely on—and the Service has not needed to apply—the 754 election revocation regulation. The repeal of technical terminations under the 2017 Tax Cuts and Jobs Act, however, foreclosed the ability of partnerships to default out of a 754 election, creating not only a renewed permanence of 754 elections but also a new need for guidance concerning requests for revocation. In anticipation of both partnerships’ and the Service’s need to rely more heavily on requests for 754 election revocation, this Note provides potential factors the Service might use to consider such requests and highlights other ways partnerships might still effect a 754 election revocation without Service approval

Empathic connection or addictive flight? : helping fathers in recovery from addiction develop empathic relationships with their children

This thesis explores the relationship between empathy and parenting in a sample of fathers recovering from addiction. It considers whether and how the development of empathic parenting skills can facilitate changes in emotion regulation and positive attachment to their children, and considers the implications of focusing on supporting men as fathers for their recovery. Previous research has identified reduced capacities for empathy and emotion regulation in people experiencing addictions compared to those without addictions. The present study investigated firstly whether differences in attachment, empathy and emotion regulation would correlate with the presence or absence of addiction in a sample of fathers. Having established this to be the case, particularly with respect to empathy and emotion regulation, phase 2 of this study explored whether training in empathic parenting skills could help fathers undergoing treatment for addictions to improve their relationships with their children, their perceptions of themselves as fathers, and their sense of wellbeing. While the link between addictions in fathers and diminished health outcomes in their children is well established, there has been little research to date that has studied the perspectives of fathers themselves during the recovery process. Accordingly, this research also sought to explore the parenting experiences of a sample of fathers as they recovered from addictions in two residential rehabilitation centres in Sydney, Australia, in 2013. The focus on the men’s experiences encompassed two key questions: How do fathers recovering from addictions experience changing relationships with their children? What other changes take place for these recovering fathers throughout the parenting program? The two phases of this research were designed as a mixed-method study, consisting of an initial quantitative survey of 169 fathers who responded to questionnaires that assessed their attachment to their children, their difficulties with emotion regulation, their mental and physical health symptoms, and their social, cognitive and affective empathy. The following second phase was designed as an in-depth multiple case study that involved seven fathers in the two residential rehabilitation centres. The results were encouraging, as each of the seven fathers told of positive change in their lives. Through the recovery process the men described themselves and their children differently, as their children became more important to them and their confidence grew in those relationships. It was clear that fatherhood was a significant concern for these men, and their relationships with their children a central motivator for them. The men were thus able to develop greater emotion regulation themselves through learning about how their children learn to manage emotions and how they as fathers can help, in addition to emotion regulation exercises focusing on their own wellbeing as fathers. The change in the fathers’ comments and questionnaire responses between the beginning and end of the parenting program also showed evidence of closer empathy-related attachment (‘empathic connection’) to their children, which is thought to underlie both the recovery process and their relationships with their children. The implications of these results are profound. Firstly, this study has found that men with major histories of addiction still have the ability, with positive support and improved emotional awareness, to form an empathic connection with their children. Secondly, providing a means for these men to focus on fatherhood within their recovery program has also helped facilitate a greater awareness of being positive role models for their children. This in turn led some of the fathers to report that their children showed not only more respect towards them, but perhaps most importantly, improved wellbeing

Influence of the lattice topography on a three-dimensional, controllable Brownian motor

We study the influence of the lattice topography and the coupling between motion in different directions, for a three-dimensional Brownian motor based on cold atoms in a double optical lattice. Due to controllable relative spatial phases between the lattices, our Brownian motor can induce drifts in arbitrary directions. Since the lattices couple the different directions, the relation between the phase shifts and the directionality of the induced drift is non trivial. Here is therefore this relation investigated experimentally by systematically varying the relative spatial phase in two dimensions, while monitoring the vertically induced drift and the temperature. A relative spatial phase range of 2pi x 2pi is covered. We show that a drift, controllable both in speed and direction, can be achieved, by varying the phase both parallel and perpendicular to the direction of the measured induced drift. The experimental results are qualitatively reproduced by numerical simulations of a simplified, classical model of the system

A nonadiabatic semi-classical method for dynamics of atoms in optical lattices

We develop a semi-classical method to simulate the motion of atoms in a dissipative optical lattice. Our method treats the internal states of the atom quantum mechanically, including all nonadiabatic couplings, while position and momentum are treated as classical variables. We test our method in the one-dimensional case. Excellent agreement with fully quantum mechanical simulations is found. Our results are much more accurate than those of earlier semi-classical methods based on the adiabatic approximation.Comment: 7 pages, 5 figures, submitted to European Physical Journal

Relationship between fish size and otolith length for 63 species of fishes from the Eastern North Pacific Ocean

Otoliths commonly are used to determine the taxon, age, and size of fishes. This information is useful for population management, predator-prey studies, and archaeological research. The relationship between the length of a fish and the length of its otoliths remains unknown for many species of marine fishes in the Pacific Ocean. Therefore, the relationships between fish length and fish weight, and between otolith length and fish length, were developed for 63 species of fishes caught in the eastern North Pacific Ocean. We also summarized similar relationships for 46 eastern North Pacific fish species reported in the literature. The relationship between fish length and otolith length was linear, and most of the variability was explained by a simple least-squares regression (r 2 > 0.700 for 45 of 63 species). The relationship between otolith length and fish length was not significantly different between left and right otoliths for all but one fish species. Images of otoliths from 77 taxa are included to assist in the identification of species. (PDF file contains 38 pages.

Explicit approximate controllability of the Schr\"odinger equation with a polarizability term

We consider a controlled Schr\"odinger equation with a dipolar and a polarizability term, used when the dipolar approximation is not valid. The control is the amplitude of the external electric field, it acts non linearly on the state. We extend in this infinite dimensional framework previous techniques used by Coron, Grigoriu, Lefter and Turinici for stabilization in finite dimension. We consider a highly oscillating control and prove the semi-global weak $H^2$ stabilization of the averaged system using a Lyapunov function introduced by Nersesyan. Then it is proved that the solutions of the Schr\"odinger equation and of the averaged equation stay close on every finite time horizon provided that the control is oscillating enough. Combining these two results, we get approximate controllability to the ground state for the polarizability system